Always just around the corner
Sabaru have for a few years now had a diesel boxer engine available for their cars yet the aviation community is still without a good Jet A1 boxer engine for its aircraft as an alternative to the popular petrol Lycoming or Continental. What happened to the promise of cheap clean quiet low maintenance (at least 2000 hours between overhaul) piston diesel aero engines that seemed to be just around the corner 5 years ago? Low cost Jet A1 for everybody and perhaps ordinary car/lorry fuel bought from the garage forecourt for those that wanted to use it. It seemed like only a question of a couple more years of LL100 and we would all be moving over to Jet A1 for the average spam can such as a Cessna 150, 172 or PA28. However, they still seem to be just around the corner and not getting any closer.